LED (Light Emitting Diode), light emitting diode, is a solid state semiconductor devices, it can be directly to the electrically converted to light. The heart of LED is attached to a bracket on one end of a semiconductor chip, the chip, is the negative side, and the other end connected to the positive power supply, so that the whole wafer is epoxy encapsulated. The semiconductor wafer is composed of three parts, the part of the P-type semiconductor, the hole in it dominant, and the other end is an N-type semiconductor, in the side of the main electronic, the intermediate is typically 1-5 cycles of the quantum well. When the current through the wire in the chip, the electrons and holes will be pushed to the quantum well, electron hole recombination in the quantum well, and will be issued in the form of photons of energy, which is the principle of LED luminous. And the wavelength of light that is the color of the light is determined by the material to form a PN junction. .
 
LED technology overview: L
LED (Light Emitting Diode), light emitting diode, referred to the LED, is a way to convert electrical energy into visible light solid state semiconductor devices, it can be directly put electricity into light. The heart of LED is a semiconductor wafer, the wafer is attached to one end to a bracket on one end of the negative electrode, and the other end connected to the positive power supply so that the whole wafer is epoxy encapsulated. The semiconductor wafer is composed of two parts, a part is a P type semiconductor, the hole in it dominant, the other end is an N-type semiconductor, in the side of the main electronic. But the two semiconductor linking between them to form a "PN junction. When the current through the wire act on the chip, the electron will be pushed to the P region, the P zone electron hole recombination, then will be issued in the form of photons of energy, this is the LED light-emitting principle. And the wavelength of light that is the color of the light is determined by the material to form a PN junction. It is a way through the to control semiconductor light-emitting diode display, used to display a variety of information, text, graphics, images, animation, quotes, video, video signal display screen. With easy to control, low voltage DC drive, a combination of rich color performance, long life and other advantages, widely used in various projects in the city, large screen display system. LEDs can be used as a display, under computer control, thousands of videos and pictures of the color change. LED is a way to convert electrical energy into visible light semiconductor.
LED epitaxial wafers process:
Over the last decade, in order to develop a blue high-brightness light-emitting diodes, the research staff around the world are all fully engaged. Commercialization of products, such as blue and green light-emitting diode LED and laser diode LD application to explain all the hidden potential of the group III-V elements. Current commercialization of the material of the LED and its epitaxial technology, most of the red and green light-emitting diode of the epitaxial techniques for liquid-phase epitaxial growth method based, yellow, orange light-emitting diode is currently still the growth of the vapor phase epitaxial growth method GaAsP GaAsP based materials.
Generally, the growth of GaN requires high temperature to break the key solution of NH3 of NH, the other hand by the dynamics simulation also learned NH3 and MO Gas produces no volatile byproducts of the reaction will be conducted.

 LED

Epitaxial wafer process is as follows:
Substrate - Structural Design - buffer layer growth - the growth of N-type GaN layer - multi-quantum well light-emitting layer green - a P-type GaN layer growth - annealing - detection (light, fluorescence, X-ray) - epitaxial films
Epitaxial wafers - design, the processing mask - lithography - ion etching - N-type electrode (coating, annealing, etching) - p-type electrode (coating, annealing, etching) - Dicing - chip sorting, grading

Specifically described as follows:

Fixed: silicon rods fixed in the processing stage.
Slice: silicon rods cut into precise geometry of the thin silicon wafers. Silicon powder produced in this process with Shuilin, generate wastewater and silicon slag.
Annealing: duplex thermal oxidation furnace, after nitrogen purge, using infrared heating to 300 to 500 ° C, the silicon wafer surface and oxygen react, so that the silicon formed on the surface of the silica protection layer.
Chamfer: annealed silicon wafer trimmed to a circular arc-shaped, to prevent the wafer edge cracking and the lattice defect, and increase the degree of flatness of the epitaxial layer and the photoresist layer. Silicon powder produced in this process with Shuilin, generate wastewater and silicon slag.
Sub-file detection: In order to ensure the specifications and quality of the wafers, and detection. Here will produce waste.
Grinding: grinding tablets to remove the slices and round mill the creatures saw marks and surface damage layer, effectively improve the silicon wafer curvature, flatness, parallelism, to achieve the specifications of a polishing process can handle. This process produces waste grinding tablet.
Wash: the dissolution of the organic solvent, the combination of ultrasonic cleaning technique to remove the organic impurities of the silicon surface. This process produces organic waste gas and waste organic solvents.
RCA cleaning and removal of particulate matter and metal ions of the surface of the wafer: cleaning by a multi-channel.
The process is as follows:
SPM cleaning: H2SO4 solution and H2O2 solution in proportion dubbed SPM solution, the SPM solution has a strong oxidation ability, metal oxide dissolved in the cleaning fluid, and oxidation of organic pollutants into CO2 and H2O. SPM wafer cleaning to remove the organic silicon surface dirt and part of the metal. This process will produce sulfuric acid mist and spent sulfuric acid.
DHF cleaning: with a certain concentration of hydrofluoric acid to remove the natural oxide film of the silicon surface, and the adhesion of the metal in the natural oxide film can also be dissolved into the cleaning solution while DHF the formation of the oxide film is suppressed. This process produces hydrogen fluoride and waste hydrofluoric acid.
APM cleaning: the APM solution by a certain percentage of NH4OH solution, H2O2 solution, the surface of silicon oxide film (about 6nm were hydrophilic) Since the H2O2 oxidation, the oxide film is NH4OH corrosion, corrosion immediately and oxidation oxidation and corrosion is repeated, and the particles and a metal adhered to the surface of the wafer with the etching layer falls within the cleaning liquid. Here to produce ammonia and waste ammonia. HPM cleaning: HPM, composed by a certain percentage from the HCl solution and H2O2 solution for removing the surface of the silicon, sodium, iron, magnesium, and zinc and other metal contaminants. This process produces hydrogen chloride and waste hydrochloric acid.
DHF cleaning: removing a step on the oxide film on the silicon surface. Whe detection: the detection of the quality of the silicon wafer after polishing, RCA cleaning, does not meet the requirements from new the grinding and RCA cleaning.
Corrosion A / B: The mechanical processing such as slicing and grinding, the wafer surface by the processing stress and the formation of damaged layer, is typically removed by chemical etching. Corrosion A is the acidic corrosion damage layer is removed with a mixed acid solution, producing hydrogen fluoride, NOx and waste acid mixture; corrosion B is an alkaline etch, with sodium hydroxide solution to remove the damage layer, resulting in waste lye. Part of the project wafers using corrosion A part by etching B. Sub-file monitoring: re-corrosion damage detection for damage silicon wafers.
Rough polishing: single use abrasives to remove the damaged layer, generally to remove the amount of 10 ~ 20um. Here produce the rough polishing liquid waste.
Fine polishing: fine grinding agent to improve the micro-roughness of the silicon surface, generally remove the amount of less than 1 um, and thus to the high flatness of silicon. Produce fine polishing liquid waste.
Detection: Check silicon wafers to meet the requirements, which do not meet from new polishing or RCA cleaning. Detection: View the silicon surface is clean, surfaces such as dirty from the new scrub until clean.
Packaging: monocrystalline silicon polished wafer packaging.
Before the chip to produce a small chip, is a relatively large epitaxial wafers, chip production process cutting this fast epitaxial wafer is cut into small chips. It should be LED production process of a link in a